Lecture 16 Kidney Toxicity Flashcards
What is a biomarker?
A defined characteristic that is measured as an indicator of processes or responses
Creatinine is a functional biomarker, what does this mean?
Represents the function of the kidney: creatinine is eliminated by kidney, if dysfunctional creatinine will accumulate
At steady state:
production = elimination = …
clearance x concentration
So concentration = production / clearnace
Technically, serum creatinine is not a marker of renal injury, but a marker of …?
Glomerular filtration rate
What is disadvantageous about serum creatinine as a biomarker?
In renal injury, takes time for GFR to drop and creatinine levels to accumulate. Better to have biomarker that peaks at time of injury.
In diagnostic/prognostic studies, what are 3 definitions that have to be made in a study?
Cohort, measurement, diagnosis/outcome
Choose a threshold cutoff, then can generate 2x2 table.
How do we calculate sensitivity?
True detected positive rate out of all true positives, a/a+c
How do we calculate specificity?
True detected negative out of all true negatives, d/b+d
What is positive predictor value PPV?
True detected positive out of all detected positives, a/a+b
What is negative positive value NPV?
True detected negative value our of all detected negatives, d/c+d
How is likelihood ratio calculated?
Sn/1-Sp
When should a high specificity test be used?
High specificity good for ruling in, don’t want to detect any false +
When should a high sensitivity test be used?
High sensitivity good for ruling out, don’t want to miss anybody so detect more than true, but ok because not final test.
True or false: different biomarkers are good for different toxins
True
Is chronic kidney disease of unknown origin a developing or developed country disease?
Developing country
